The staff were friendly and welcoming during my week at the Centro Hotel Atlanta. Breakfast room was nice, and a typical German breakfast with lots of cold meats, cheeses and bread. There's no bar at this hotel, but the vending machine in the lobby has plenty of beer … so you just make it work. Reasonably convenient location, a 10-15 minute walk to either the Hauptbahnhof or Kropcke station.
The reason I have left a neutral review of the hotel is that it appears like there are two hotels in one here. The modern, light-filled, clean room shown in the photo is NOT like the room myself and my colleague had when we stayed. The room & the bed were REALLY old, but appeared acceptably clean, though the carpet was old, tired and stained. The bathroom however, was horrible. The shower had lots of mould around the base and shower door frames. The sink was starting to rust just around the plug hole and it just wasn't a pleasant experience to be in there at all.
It definitely spoilt my experience, especially at the HIGH nightly rate because EuroBLECH was on. As a business traveller, you have little choice in Hannover when a big fair is on, though it's not acceptable when you book a room based on a photo and then get NOTHING like what you expect.